Do a Google search for free 3DS objects of the type you want, and use the 3DS Import goodie (Help > Goodies if you do not have it installed) to convert to GDL.
Search these forums - there are lots of posts for sites for free objects and for doing 3ds conversion.
Since this isn't really a wish, I'm moving this to the Libraries forum.
Karl
One of the forum moderators
AC 27 USA and earlier • macOS Ventura 13.6.9, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB